Looking for info on McCluskey's in Fermanagh Ireland

Hello, my name is Colleen McCluskey-Douse from Prince Edward Island Canada, I have traced my roots here back to this couple and have found their gravestone in Fodhla Cemetery, Iona PEI. Patrick McCluskey born 1816 Fermanagh Ireland died 26 July 1864 and Ellen Dougherty born Ireland 1819, died 4 December 1884.
In Brendan O'Grady's book "Exiles and Islanders" He states that, "Aboard the plague ship the Lady Constable were two couples who had set out from Roslea intending to raise their families in Iona: Patrick McCluskey and his wife Ellen Dougherty, and Philip Rooney and his wife Mary Dougherty. Of the four Rooney sons born in Ireland, three died en route."
The Lady Constable left from Liverpool and arrived in PEI May 21st or 24th 1847, Patrick and Ellen's daughter Catherine was born May 21 and baptised May 24, 1847 . 25 people died en route from typhus, and 8 more died in quarantine.

I am assuming Ellen and Mary Dougherty are sisters, though I have not traced the Rooney family here yet.

I am looking for any information on these people, or if anyone knows where to start loooking. I have looked at the records for St. Tierneys Roman Catholic Chapel in the Parish of Clones, but they don't start until 1862.
Gravestones:
McCluskey, Sylvester died 29/6/1823 on a gravestone at St. Tierney's Cemetery, but I don't have any connection.
Owen McClosky d. 22/3/1741 a.----. As likewise his wife Rose who d. August a. 56
Erected by By Patrick McCluskey for the use of his family. (writing facing opposite way.)